Vapor generator with tangential firing arrangement



Dec. 21, 1965 H. M. LOWENSTEIN ETAL 9 VAPOR GENERATOR WITH TANGENTIAL FIRING ARRANGEMENT 4 Sheets-Sheet 1 Filed Dec. 13, 1961 INVENTORs: HERBERT M. LOWENSTEIN ROBERT H. WOLIN ATTORNEY Dec. 21, 1965 H. M. LOWENSTEIN ETAL 3,224,419

VAPOR GENERATOR WITH TANGENTIAL FIRING ARRANGEMENT Filed Dec. 15, 1961 4 Sheets-Sheet 2 IN VEN TORs HERBERT M. LOWENSTEIN ROBERT H WOLlN ATTORNEY 4 Sheets-Sheet 5 ffi a, w my w H. M. LOWENSTEIN ETAL VAPOR GENERATOR WITH TANGENTIAL FIRING ARRANGEMENT Dec. 21, 1965 Filed Dec. 15, 1961 INVENTORS: HERBERT M. LOWENSTEIN ROBERT H.WOLIN BY ATTORNEY Dec. 21, 1965 LQWENSTEIN ETAL 3,224,419

VAPOR GENERATOR WITH TANGENTIAL FIRING ARRANGEMENT Filed Dec. 13, 1961 4 Sheets-Sheet 4 FIG. 4

INVENTORS: HERBERT M. LOWENSTElN ROBERT H.WOLIN ATTORNEY United States Patent 3,224,419 VAPOR GENERATOR WITH TANGENTIAL FIRING ARRANGEMENT Herbert M. Lowenstein, Windsor, and Robert H. Wolin, Avon, Conn., assignors to Combustion Engineering, Inc, Windsor, Come, a corporation of Delaware Filed Dec. 13, 1961, Ser. No. 159,039 14 Claims. (Cl. 122-478) This invention relates generally to high capacity vapor generators and has particular relation to such generators utilizing the tangential firing system.

In the typical so-called tilting tangential firing arrangement, such as shown and described in US. Patent 2,697,422 issued December 21, 1954, fuel and air are introduced throughout a vertically elongated burner zone into an upright fluid cooled furnace in a manner to create a rapidly rotating gas mass which rotates about the vertical axis of the furnace. The burner zone is located remote from the furnace outlet and by means of the tilting feature of the burners the combustion zone may be adjusted, within limits, toward and away from the furnace outlet to provide a desired vapor temperature control. The tangential burner firing arrangement consists generally of a vertically elongated burner box extending throughout the height of the burner zone with there being a plurality of such boxes symmetrically arranged about the furnace and with each of these boxes having disposed therein fuel and air projecting nozzles at space locations throughout their height. Fuel and air are projected from each of these burner assemblies in a direction tangent to an imaginary vertical cylinder generally coaxial with the furnace, with the nozzles being tiltable to vary the direction to the horizontal of the fuel and air streams.

Modern vapor generators are becoming exceedingly large developing several million pounds of steam per hour and in these very large units the fuel projecting nozzles are correspondingly large with pulverized coal nozzles approximately 2 ft. square now being employed. The larger these fuel streams become, the more difiicult it is to provide adequate contact betwen the fuel and the air for efiicient combustion, particularly with regard to the centermost portions of the fuel stream. In addition to this problem, there is the problem with these very high capacity units of providing sufiicient height between the furnace outlet and the end of the burner zone nearest thereto for burning of the fuel. It is necessary to have sufiicient height to insure adequate burning of the fuel in the furnace so that there will not be any substantial burning in the gas pass which extends from the furnace outlet. With the very long burners or burner assemblies necessary in the high capacity units (such as 30 feet or more) it may be necessary to increase the vertical dimension of the furnace merely to provide sufficient distance between the furnace outlet and the burner zone for proper burning of the fuel.

The present invention is directed to providing an improved tangential firing arrangement for high capacity units which will overcome the aforementioned difficulties and provide additional advantages as well. In accordance with the invention there is provided a pair of assemblies adjacent each corner in lieu of the previously utilized single assembly. Each of the assemblies in the pair are generally coextensive and while placed in side-by-side relation are somewhat laterally spaced from each other. With this arrangement the height of the burner or firing zone may be considerably reduced and at the same time the size of the fuel streams that are projected from each of the assemblies may be substantially smaller than would otherwise be the case for burning the same quantity of fuel. With the improved arrangement of the invention better utilization of the furnace volume may be had as well as a more economic construction utilized, with the vertical extent of the furnace being less than would otherwise be required. Not only may the burning efficiency be improved and the over-all furnace height reduced with the present invention, but it is possible to provide an improved control by means of burner tilt in certain installations over that otherwise utilized and also to provide an improved arrangement for operating under slagging conditions where the slag is maintained molten and is continuously or intermittently withdrawn from the lower region of the furnace. With regard to this slagging operation, the lower fuel nozzles in one of the burner assemblies of each pair may be supplied from one fuel source, such as a fuel pulverizer while the fuel nozzle of the other burner assemblies may be supplied from a separate fuel source, thereby providing a safety feature so that if one source of fuel fails it will not render inoperative the lower set of burners in all of the burner assemblies, thereby insuring that such failure will not cause a solidification of the slag and accordingly the malfunction of the unit.

Accordingly, it is an object of this invention to provide an improved high capacity vapor generator utilizing the tangential firing system.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned object in view, the invention comprises an arrangement, constructing and combination of the element of the inventive organization, in such a manner as to attain the results desired and hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawings wherein:

FIG. 1 is a vertical sectional view somewhat diagrammatic in nature showing a high capacity vapor generator embodying the present invention;

FIG. 2 is a transverse sectional view showing the pair of burner assemblies mounted in side-by-side spaced relation at each of the corners at the furnace;

FIG. 2A is a diagrammatic representation in nature of a transverse furnace section showing the connection of one of the mills with the burner;

FIG. 3 is a front elevational view, fragmentary in nature, showing one pair of burner assemblies mounted in a furnace corner;

FIG. 4 is a vertical sectional view, also fragmentary in nature, showing the detailed construction of one of the burner assemblies with this view being taken generally along line 44 of FIG. 3;

FIG. 5 is a fragmentary vertical sectional view showing the lower region of the furnace in a modified arrangement wherein the furnace is of the slagging type as contrasted with the dry bottom organization of FIG. 1; and

FIG. 6 is a transverse sectional view of the modified organization of FIG. 5 and is taken generally along line 66 of FIG. 5.

Referring now to the drawing, wherein like reference numerals will be used throughout to designate like elements, the illustrative and preferred embodiment of the invention as depicted therein comprises a high capacity vapor generator having a furnace 10 that is fired in its lower region with the combustion gases thus generated passing up through the furnace and through an outlet at the upper end of the rear wall thereof and from which extends the lateral gas pass 12, which in turn connects with the upper end of the vertically extending gas pass 14. The combusition gases after leaving the furnace pass through the gas pass 12 and then down the gas pass 14 traversing the heat exchange surface disposed in these gas passes with the combustion gases passing from the lower end of gas pass 14 to suitable point of discharge.

In the lower region of gas pass 14 is positioned the economizer 16 with feedwater being forced through the economizer from feed pump 18, the feedwater being conveyed from the economizer 16 via conduit 20 to the chamber 22. From chamber 22 the primary fluid passes down through conduit 24 within which is disposed the pump 26 with the primary fluid being conveyed to the headers 28 at the lower region of the furnace and with which the tubes 30 which line the four walls of the furnace are effectively connected.

The primary fluid passes from the headers 28 up through the furnace wall tubes to suitable headers, such as 32, at the upper end of the furnace and with which the upper ends of the furnace wall tubes are connected. From these headers the primary fluid is conveyed by con duits 34 to the chamber 22. Extending from this chamber 22 is a conduit or conduits 36 which convey the primary fluid to the low temperature vapor heater section 38. From this low temperature vapor heater section the primary fluid is conveyed through conduit 39 to the high temperature vapor heating section 40. Disposed within the conduit 39 may be a spray type desuperheater 42. After traversing the high temperature vapor heater section 40 the primary fluid is heated to its desired temperature and is conveyed from this heating section through conduit 44 to the high pressure stage of the turbine 46.

The vapor generator in the illustrative arrangement employs the reheat cycle with the vapor after passing through the high pressure stage of turbine 46 being conveyed back to the vapor generator through conduit 48 for reheating to a desired high temperature by means of the reheater 56. From the reheater, the vapor is again conveyed to turbine 46 through conduit 51 for passage through the low pressure stage of the turbine.

The exhaust from turbine 46 is received in condenser 59' Where the vapor is condensed and condensate pump 52 pumps the condensate from the condenser 59 through the feedwater heaters 54 and various other equipment, if desired,.such as deaerators and finally to the feed pump 18.

The various heat exchange surfaces over which the combustion gases pass such as the primary vapor heating sections, the reheater and the economizer are comprised of sinuous bent tubular elements disposed in rows which are spaced across the gas stream as is conventional in heat exchange organizations ofthis type.

In accordance with the invention the tilting tangential system of firing is employed, with this system being well known and utilizing a plurality of vertically elongated burner assemblies which are symmetrically arranged about the perimeter of the furnace at the firing zone and preferably adjacent to :the furnace corners. These burner assemblies direct streams of fuel and air in a direction that is tangent to an imaginary vertical cylinder coaxial of the furnace so that a burning mass is created which is quite turbulent and which rotates about the furnace axis.

In the illustrative organization the firing zone is identified as A with fuel and air being introduced into furnace throughout the vertical extent of this region. In accordance with the invention there is disposed at each of four locations, i.e., at each of the four corners of the furnace, a pair of burner asemblies identified generally as 56 and each of which extends throughout the vertical height of the firing zone A with the assemblies of each pair being in close but spaced relation.

In the illustrative arrangement each of the four corners of the furnace is chamfered sufficiently to permit mounting of the pair of adjacent assemblies 56 in the charnfered portions so that the fuel and air from the adjacent assemblies is projected through the wall portion of these chamfered corners. The furnace wall tubes 30 in the regions of the burner assemblies are suitably bent and arranged in relation to each other to permit the mounting of the closely spaced assemblies in the chamfered corner portions. The tube arrangement at the location of thebur'ner assemblies is best shown in FIG. 2.

Each of the burner assemblies comprises a plurality I of tiltable air nozzles and a plurality of tiltable fuel nozzles arranged alternately in vertically spaced relation. The number of fuel and air nozzles required will vary with the capacity of the unit although it will be understood that with the size of the units with which the present invention is concerned there will be numerous such vertically spaced nozzles. Solely for the purpose of providing a clear illustration only a few nozzles have been shown in the FIG. 1 illustration with it being understood that this is merely diagrammatic and that in a unit employing the present invention many more nozzles than are shown in this FIG. 1 Will be utilized.

As shown in the fragmentary sectional view of FIG. 4 the burner assembly comrpises pulverized coal burning units 57, oil burners 58 and the air directing nozzles 60. All this equipment is mounted in a suitable burner box or housing 62 and each of the pulverized coal burning units 57 includes the duct 60 which receives coal in an air stream from a suitable source, i.e., a pulverizer, with there being mounted at the end of the duct 60 the pivotal nozzle 62. The oil burner 58 includes a pivotally mounted tip 64 which receives its oil supply through the pipe 66. Conbustion supporting air, preferably heated by means of the combustion gases that exit from the gas pass 14, is conveyed to the windbox 68 which forms a part of each of the burner assemblies with this hot air being directed to the windbox by means of the ducts 70. From the windbox the air is conveyed into the burner box or housing 62 so that this air surrounds both the pulverized fuel burning units 57 and the oil burner 58. Each of the tiltable nozzles of the pulverized coal burning units includes at its outer regions air directing means as well as the stream of pulverized fuel. The pivotally mounted fuel and air nozzles are each pivotally adjustable about a horizontal axis through suitable links and levers identified generally as 72 with simultaneous adjustment of the nozzles in a particular assembly being effected by means of the actuating bar 74.

Each. of the pair of burner assemblies 56 in each corner may be oriented so that they project their fuel and air stream tangent to a common vertically disposed imaginary cylinder that is coaxial of furnace 19 or, alternatively, one of the burner assemblies of each pair at the furnace corners may be mounted so as to direct streams of fuel and air tangent to one such imaginary vertically disposed cylinder while the other pair of assemblies may direct fuel and air streams tangent to such an imaginary cylinder of substantially different diameter. This arrangement is illus trated in FIG. 2 and in such arrangement it is preferred to have the downstream assemblies of each pair relative to the direction of rotation of the burning mass be directed at the larger diameter cylinder. This latter arrangement may have the advantage of utilizing to greater advantage the full area or volume of the furnace for the burning of fuel.

Each of the pair of assemblies at each corner of the furnace are laterally spaced so as to permit air to enter the space between the fuel streams issuing from this pair of assemblies, thereby facilitating contact of the fuel and air in this arrangement. Furthermore, the spacing of the adjacent burner assemblies in the manner disclosed permits an ignitor torch organization identified generally as 76 to be mounted between the assemblies with this providing a more economical arrangement and construction than would otherwise be the case. This ignitor torch organization, the outlet end of which is shown in FIG. 3 and is identified as 78 provides an ignitor flame directed toward each of the burner assemblies for the purpose of igniting these main burner assemblies and, under certain conditions, where unstable flame conditions might exist, pro-. viding for safety of operation,

It will be appreciated that by providing a duel set of burner assemblies in spaced but close relation at each corner of the furnace the height of the burner assemblies required to introduce the necessary fuel into the furnace for generating the vapor for which the unit was designed will be substantially less than the single burner organization heretofore employed while at the same time the size of the fuel nozzles may be substantially smaller than those otherwise necessary, reducing the difficulty of providing adequate contact between the fuel and the air and particularly between the fuel in the center portions of the fuel streams.

In supplying fuel to the organization of FIG. 1, which is a dry bottom furnace, each set of fuel nozzles in all of the assemblies which are at a common elevation are preferably supplied from a common source, with the pulverizedcoal burning units being supplied from a common mill. The pulverized coal is passed from the mill 80 through the transporting conduits or ducts 82 to the burning units in each of the corners which are in a common horizontal plan with FIG. 2A showing the mill to burner distribution.

This arrangement has a number of advantages including providing the simplest and most economic piping arrangement.

In lieu of providing a dry bottom type of operation the furnace may be of the wet bottom type with this modified arrangement being shown in FIGS. 5 and 6. This furnace construction is generally the same as that of FIG. 1 except that in lieu of the hopper bottom provided in the FIG. 1 arrangement the wet or slagging bottom organization of FIG. 5 has a generally flat bottom portion 83 having a slag tap opening 84 located therein with this opening being disclosed as centrally located. In the slagging bottom type of operation it is advantageous to supply one of the lowermost burner units 57 in each pair of burner assemblies at the furnace corners from one source, i.e., one pulverizing mill and supply the lower burning unit of the other assemblies of each pair from a separate and different source, i.e., a separate and different mill. The reason for this is that these lowermost burner units are effective to maintain the slag at the bottom of the furnace in a molten state so that it will freely run to the slag tap opening 8-4. In the event that one of the mills that supply the lowermost burner units in one assembly of each pair becomes inoperative for some reason these lower units of the other assembly of each pair will remain in operation and thereby prevent the slag from freezing. In the FIG; 6 illustration the mill 86 supplies the lower pulverized coal burner units 57 of one assembly 56 at each corner and the mill 88 supplies the lower pulverized coal burner units of the other assemblies.

By means of the tiltable nozzles which form part of each burner assembly the zone of combustion in the furnace may be adjusted toward or away from the furnace outlet. This, in turn, permits the temperature and accordingly the heat content of the gases that pass from the furnace and over the heat exchange surface in the gas passes to be regulated, within limits. It is the general characteristic of vapor generators to which the invention pertains that the temperature of the vapor heated by convection heat exchange surface tends to decrease as the load is decreased. Accordingly the tilting burner type of control is adjusted to raise the zone of combustion in the furnace with decreasing loads and accordingly thereby tending to prevent this decrease in vapor temperature. For instance, the temperature of the reheat vapor being conveyed to conduit 51 from turbine 46 may be sensed through suitable instruments and the tilt of the burner assemblies 56 control so as to maintain this temperature generally at its desired value with varying load.

In the organization of the invention wherein dual burner assemblies are provided at each of the burner corners it is advantageous to control the two assemblies at each corner independently. This will enable a better control of the vapor temperature than would be provided if all of the burner assemblies were controlled together. For instance, in the illustrative organization of FIG. 2, the fuel and air directing nozzles of assemblies (referred to as group A for identification) directing fuel and air streams tangent to the larger diameter imaginary cylinder 61 may be tilted in an upward direction as the load decreases from its maximum value while the fuel and air directing nozzles of the assemblies (referred to as group B for identification) directing fuel and air streams towards the smaller diameter imaginary cylinder 63 may remain unchanged; or the fuel and air directing nozzles of the group B may be adjusted upwardly at a substantially lesser rate than those of group A with the operation being reversed when the load is increased from a value below maximum value; or group B may be adjusted for upward tilting only after group A has been tilted upwardly to their limit, with this operation also being reversed when the load is increased from a value below maxi-mum. i.e., as the load is increased group B will-be tilted downwardly to their lower limit after which group A will be tilted downwardly. These operations will enable a greater utilization for the furnace volume for the burning of the fuel and yet will provide an effective control of vapor temperature. It is noted that by adjusting the fuel and air streams which are directed to the larger diameter cylinder and accordingly which are most effective in regard to transmitting heat to the furnace wall tubes the most effective control for the vapor temperature is provided. Thus while the burning fuel portion which is most sensitive with regard to heat absorption of the furnace wall tubes may be adjusted longitudinally of the furnace the innermost burning fuel portion which is least sensitive in this regard and accordingly least effective as a control for vapor temperature may remain relatively unchanged or be adjusted upwardly toward the furnace outlet at a slower rate or only after the full extent of the adjustment of the outer fuel portion is obtained so that a more optimum utilization of the furnace volume for burning of the fuel is provided. It will be understood that if it is so desired, as for simplicity of construction and control, all the burner assemblies may be tiltably adjusted simultaneously and to the same degree.

With the organization of the present invention the overall length of the burner organization required to burn a given amount of fuel per unit time in a furnace is substantially reduced. While at the same time it is possible to provide for more efficient burning of the fuel and more efiicient utilization of the furnace volume. The furnace itself may be of subtantially less length than was heretofore required and with the problem of providing sufiicient furnace length to insure that no substantial burning will take place in the gas pass extending from the furnace being greatly alleviated.

While we have illustrated and described a preferred embodiment of our invention it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. We, therefore, do not wish to be limited to the precise details set forth but desire to avail ourselves of such changes as fall within the purview of our invention.

We claim:

1. In a vapor generator the combination of an upright elongated furnace of polygonal transverse section having its walls lined with heat exchange tubes and having a gas outlet adjacent one end from which extends a convection gas pass, a convection vapor heater in said gas pass, said furnace being fired by pulverized coal and being provided with tilting tangential firing means comprised of burner means adjacent each of the furnace corners operative to project pulverized coal and air into the furnace to create a whirling mass of burning fuel rotating about the furnace axis and which mass is vertically adjustable toward and away from the furnace outlet, each of said 7 burner means being comprised of a first and a second vertically elongated, generally coextensive burner assembly with said first and second assembly being in closely spaced relation and extending vertically throughout a substantial length of the furnace, said assemblies including. means for projecting fuel into the furnace at a plurality of vertically spaced locations with the locations of the several burner means being arranged in tiers so that the fuel is projected from the burner means into the furnace in vertically spaced tiers, said assemblies also includingmeans to project air into the furnace, each of said assemblies including means to adjust the angle of dischargeof the fuel and air with respect to the horizontal to vary the vertical position of the burning fuel mass, means for supplying pulverized coal to said assemblies with fuel projecting means of said first assemblies receiving fuel from a common source and fuel projectingmeansof said second assemblies also receiving fuel from a common ource.

2. A vapor generator including an upright furnace of polygonal transverse section and having its walls lined with heat exchange tubes, said furnace having a gas outlet adjacent one end and from which extends a convection gas pass, a convection vapor heaterreceived insaid gas pass, means for firing said furnace in a manner to create a mass of burning fuel whirling about thevertical axis of the furnace and adjustable longitudinally of the furnace so as to vary the heat content of the gases passing over the convection vapor heater to provide a control for the vapor temperature, this means being comprised of pulverized coal burner means adjacent each of the furnace corners, each of these burner means including a plurality of vertically spaced directing nozzles received and arranged in a first vertically elongated burner'box and a similar nozzle arrangement arranged in a second vertically elongated burner box in relatively closely spaced, side-by-side relation with said first box, the vertically spaced nozzles of the several burner means being disposed in common vertically spaced horizontal planes so that streams of 'fuel are projected from the general region of the furnace corners in these planes, means operative to independently adjust the nozzles in each of the burner boxes to-vary the angle of discharge of the fuel with relation to the horizontal, a plurality of coal pulverizing means and the nozzles in one of the burner boxes in each of the burner means and at each of the vertically spaced locations being connected to receive pulverized coal from the same pulverizing means.

3. The organization of claim 2 wherein the furnace is of the dry-bottom type with all of the nozzles discharging pulverized coal into the furnace at the same vertical location being effectively connected with and supplied by a common coal pulverizing means.

4. The organization of claim 2 wherein the furnace is of the wet-bottom type with slag collecting on the furnace bottom in a molten condition during operation of the unit, the furnace being provided at its lower regionwith a discharge opening formolten slag, the burner means being located sufficiently near the furnace bottom so that the slag will remain molten during operation of the furnace, the lowermost fuel nozzles in one of the burner boxes of each burner being supplied by a common fuel pulverizing means and the lowermost fuel nozzles in the other burner box of each burner means being supplied by a different but common fuel pulverizing means.

5. A vapor generator comprising an upright elongated furnace having its walls lined with heat exchange tubes and provided with an outlet adjacent one of its ends, a convection gas passageway extending from said outlet and having therein a convection vapor heater, means firing said furnace in a tangential manner and whereby the zone of combustion may be adjusted longitudinally of the furnace toward and away from said outlet to vary the heat content of the gases traversing said heat exchanger to provide a control for the temperature of the vapor transversing the same, said means including a plurality of burner means adjacent the corners of the furnace and which project fuel and air into the furnace to create said whirling mass, each of said burner means being comprised of a first and a second burner assembly which are fuel assemblies of each burner means being operative to direct an igniter flame into the fuel and air discharge of said fuel assemblies, and means for supplying fuel to each of the assemblies of each burner means.

6. A vapor generator including a vertically elongated furnace having heat exchange tubes lining its walls and having a combustion gas outlet adjacent onelend, agas passageway extending from said outlet and having disposed therein a vapor heating heat exchanger, burner means adjacent each of the corners of the furnace and extending throughout a generally common vertical extent of the furnace projecting fuel and air into the furnace in a manner to create a whirling mass rotating about the vertical axis of the furnace, each of said burner means including a first burner assembly and a second burner assembly with these assemblies being vertically generally coextensive and disposed in spaced side-by-side relation, the upstream assembly with relation to the direction ,of rotation of the burning mass directing fuel tangent to a first imaginary vertically disposed cylinder centrally of the furnace and the other burner assembly directing fuel and air tangent to a second imaginary cylinder with said second cylinder having a diameter substantially larger than that of the first cylinder, and means for varying the angle to the horizontal of the discharge of fuel and air from the first and the second assemblies of each of the burner means.

7. The organization of claim 6 wherein each of the burner assemblies of the burner means is independently adjustable to independently vary the angle of discharge of the fuel and air with regard to the horizontal so that the assemblies which discharge tangent to the larger cylinder may be adjusted independently of those directing fuel and air tangent to the smaller diameter cylinder.

8. In a vapor generator having a vertically elongated furnace and having heat exchange tubes lining the walls thereof with there being a combustion gas outlet adjacent one end and a vapor heater over which the combustion gases egressing from the furnace pass, the method of operation comprising introducing streams of fuel and air into the furnace tangent to an imaginary vertical cylinder so as to create a whirling mass of burning fuel rotating about the vertical axis of the cylinder with these streams of fuel and air being projected from adjacent the furnace corners and throughout a substantial vertical extent of the furnace, projecting other streams of fuel and air generally from location adjacent those of the first projected streams and directing these additional streams tangent to an imaginary vertical cylinder coaxial of the furnace and having a diameter substantially larger than that of the first-mentioned cylinder, regulating the firing rate of the generator so as to meet the load requirement thereon and varying the angle to the horizontalof said additional streams in accordance with varying load so as to tend to maintain the temperature of .the vapor egressing from the vapor heater constant while maintaining the angle of discharge of the first-mentioned streams fast.

'9. In a vapor generator having an elongated furnace and having heat exchange tubes lining the walls thereof with there'being a combustion gas outlet adjacent one end and a vaporheater over which the combustion gases egressingsfrom the furnace pass, the method of operation comprising introducing a first group of streams of fuel and air into the furnace at a region remote from said outlet and tangent to an imaginary cylinder generally coaxial of the furnace so as to create a whirling mass of burning fuel rotating about the axis of the cylinder with these streams of fuel and air being projected from symmetrically disposed locations about the perimeter of the furnace and with there being a plurality of such streams at each such location in consecutive relation longitudinally of the furnace and throughout a substantial longitudinal extent of the furnace, projecting a second group of streams of fuel and air generally from location adjacent those of the first group and directing this second group tangent to an imaginary cylinder also generally coaxial of the furnace and having a diameter substantially larger than that of the first-mentioned cylinder, with there also being a plurality of such streams in said second group at each such location and in consecutive relation longitudinally of the furnace, regulating the firing rate of the generator so as to meet the load requirement thereon and varying the angle to a plane normal to the furnace axis of said second group of streams to direct said streams further toward the furnace outlet as the load decreases from maximum until such adjustments reach a predetermined degree and thereafter varying the angle of the first group of streams in similar fashion.

10. In a vapor generator having an elongated furnace and having heat exchange tubes lining the walls thereof with there being a combustion gas outlet adjacent one end and a vapor heater over which the combustion gases egressing from the furnace pass, the method of operation comprising introducing a first group of streams of fuel and air into the furnace at a region remote from said outlet and tangent to an imaginary cylinder generally coaxial of the furnace so as to create a whirling mass of burning fuel rotating about the axis of the cylinder with these streams of fuel and air being projected from symmetrically disposed locations about the perimeter of the furnace and throughout a substantial longitudinal extent of the furnace, projecting other streams of fuel and air generally from locations adjacent those of the first projected streams and directing these additional streams tangent to an imaginary cylinder also generally coaxial of the furnace and having a diameter substantially larger than that of the first-mentioned cylinder, regulating the firing rate of the generator so as to meet the load requirement thereon and varying the angle to a plane normal to the furnace axis of said first and second group of streams to move the zone of combustion toward the furnace outlet as the load on the generator decreases with the rate of adjustment of the angle of the first group being substantially less than that of the second group.

11. In a vapor generator having an elongated furnace and having heat exchange tubes lining the walls thereof with there being a combustion gas outlet adjacent one end and a vapor heater over which the combustion gases egressing from the furnace pass, the method of operation comprising introducing a first group of streams of fuel and air into the furnace at a region remote from said outlet and tangent to an imaginary cylinder generally coaxial of the furnace so as to create a whirling mass of burning fuel rotating about the axis of the cylinder with these streams of fuel and air being projected from symmetrically disposed locations about the perimeter of the furnace and throughout a substantial longitudinal extent of the furnace, projecting other streams of fuel and air generally from locations laterally adjacent those of the first projected streams and directing these additional streams tangent to an imaginary cylinder also generally coaxial of the furnace and having a diameter substantially larger than that of the first-mentioned cylinder, regulating the firing rate of the generator so as to meet the load requirement thereon and varying the angle to a plane normal to the furnace axis of said first and second group of streams to move the zone of combustion toward the furnace outlet as the load in the generator decreases with adjustment of the streams being simultaneous and to the same degree.

12. A vapor generator having a vertically disposed furnace of rectangular transverse section, the furnace having a combustion gas outlet at its upper region and being fired with pulverized coal at a region remote from said outlet, a gas passageway extending from said outlet and having a heater disposed therein, means for effecting such firing arranged to provide a roating mass of burning fuel rotating about the furnace axis and adjustable vertically of the furnace toward and from said outlet, said means including burner means adjacent each of the furnace corners, said furnace corners being charnfered to an extent sufficient to receive said burner means, each of the burner means comprising a first burner assembly and a second burner assembly with these assemblies being of similar construction, vertically coextensive and disposed in spaced relation, each of the assemblies including a plurality of vertically spaced fuel discharge and directing means, means for supplying fuel to said discharge and directing means, means for adjusting said discharge and directing means to vary the angle to the horizontal at which said fuel is projected into the fumace, said assemblies also including means for introducing air into said furnace, igniter means interposed between the two assemblies of each burner means and arranged vertically of the assemblies to provide an igniter flame directed toward the discharge from the assemblies.

13. The organization of claim 12 wherein the furnace is fired with pulverized coal, the vertically spaced fuel directing means of the several burner means are disposed in common horizontal vertically spaced planes, pulverizing means for supplying pulverized fuel to said burner means with the discharge means of each burner means located in a common horizontal plane being connected to receive pulverized coal from a common pulverizing means.

14. The organization of claim 12 wherein the furnace is fired with a slag forming fuel and is of the wet-bottom type with the slag being molten in the bottom of the furnace during operation thereof, said furnace having a slag discharge opening at its lower end, the lowermost fuel directing means of one of the burner assemblies of each burner means being supplied with fuel from a common source, and the lowermost fuel directing means of the other burner assemblies being supplied from another common source whereby interruption of one of these sources will not disrupt the supply of fuel to the lowermost furance region where high temperatures are necessary to maintain the slag molten.

References Cited by the Examiner UNITED STATES PATENTS 2,013,565 9/1935 Lundgren 122235 2,363,875 11/1944 Kreisinger et a1. 122-235 2,697,422 12/1954 Armacost 122-333 FOREIGN PATENTS 738,728 10/ 1955 Great Britain. 846,807 8/ 1960 Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

PERCY L. PATRICK, ROBERT A. OLEARY,

Examiners. 

1. IN A VAPOR GENERATOR THE COMBINATION OF AN UPRIGHT ELONGATED FURNACE OF POLYGONAL TRANSVERSE SECTION HAVING ITS WALLS LINED WITH HEAT EXCHANGE TUBES AND HAVING A GAS OUTLET AKJACENT ONE END FORMWHICH EXTENDS A CONVECTION GAS PASS, A CONVECTION VAPOR HEATER IN AID GAS PASS, SAID FURNACE BEING FIRED BY PULVERIZED COAL AND BEING PROVIDED WITH TILTING TANGENTIAL FIRING MEANS COMPRISED OF BURNER MEANS AKJACENT EACH OF THE FURNACE CORNERS OPERATIVE TO PROJECT PULVERIZED COAL AND AIR INTO THE FURNACE TO CREATE A WHIRLING MASS OF BURNING FUEL ROTATING ABOUT THE FURNACE AXIS AND WHICH MASS IS VERTICALLY ADJUSTABLE TOWARD AND AWAY FROM THE FURNACE OUTLET, EACH OF SAID BURNER MEANS BEING COMPRISED OF A FIRST AND A SECOND VERTICALLY ELONGATED, GENERALLY COEXTENSIVE BURNER ASSEMBLY WITH SAID FIRST AND SECOND ASSEMBLY BEING IN CLOSELY SPACED RELATION AND EXTENDING VETICALLY THROUGHOUT A SUBSTANTIAL LENGTH OF THE FURNACE, SAID ASSEMBLIES INCLUDING MEANS FOR PROJECTING FUEL INTO THE FURNACE AT A PLURALITY OF VERTICALLY SPACED LOCATIONS WITH THE LOCATIONS OF THE SEVERAL BURNER MEANS BEING ARRANGED IN TIERS SO THAT THE FUEL IS PROJECTED FROM THE BURNER MEANS INTO THE FURNAE IN VERTICALLY SPACED TIERS, SAID ASSEMBLIES ALSO INCLUDING MEANS TO PROJECT AIR INTO THE FURNACE, EACH OF SAID ASSEMBLIES INCLUDING MEANS TO ADJEST THE ANGLE OF DISCHARGE OF THE FUEL AND AIR WITH RESPECT TO THE HORIZONTAL TO VARY THE VERTICAL POSITION OF THE BURNING FUEL MASS, MEANS FOR SUPPLYING MEANS OF SAID FIRST ASSEMBLIES RECEIVING FUEL FROM A COMMON SOURCE AND FUEL PROJECTING MEANS OF SAID SECOND ASSEMBLIES ALSO RECEIVING FUEL FROM A COMMON SOURCE. 